Spectro-Angular Selective Emitter for Nighttime Thermoelectric Generation
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Solution Overview
Problem
Existing electrical power generation systems face inefficiencies and challenges in generating power at nighttime or in the absence of solar light, particularly due to limitations in radiative cooling and thermoelectric efficiency.
Innovation Solution
The use of a spectro-angular selective emitter coupled with a thermoelectric power generator (TEG) to optimize radiative cooling and environmental convection, along with engineered materials and structures, enhances nighttime power generation by controlling heat absorption and emission angles, thereby improving thermoelectric figure of merit and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional radiative cooling systems are used for nighttime power generation, then the system structure is simple, but the power density is low (less than 1.5 W/m2)
Solution Approach 1:
The patent applies local quality by designing the radiative cooler with spatially varying emissivity properties. The selective emitter has different emissivity values at different wavelengths and angles, optimized to maximize radiative cooling efficiency in the 8-13 μm atmospheric window while minimizing absorption at other wavelengths. This localized optimization of thermal radiation properties enables the system to achieve power density exceeding 1.5 W/m2 by creating a stronger temperature gradient across the TEG.
Solution Approach 2:
The patent employs parameter changes by optimizing key system parameters including the emissivity spectrum of the selective emitter, the area ratio between the TEG and radiative cooler, and the thermoelectric figure of merit. By tuning these parameters—particularly designing the emitter to have high emissivity in the atmospheric window and optimizing the TEG area ratio—the system achieves enhanced nighttime power generation while maintaining structural feasibility.
2Power
If the TEG area is increased to improve power generation, then the power output increases, but the area ratio optimization becomes more complex and costly
Solution Approach 1:
The patent applies partial action by optimizing the TEG area to cover only the critical central region of the radiative cooler where the temperature gradient is strongest. Rather than covering the entire radiative cooler surface, the TEG is sized to capture the most valuable thermal energy flux, achieving optimal power density without the complexity and cost of full-area coverage. This selective area optimization balances power output with system simplicity.
3Productivity
If the selective emitter is designed to control heat absorption at specific frequencies and angles, then radiative cooling efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies composite materials by constructing the selective emitter as a multi-layer structure consisting of alternating high-emissivity and low-emissivity layers. This composite design enables precise control over the emissivity spectrum through the interference and absorption characteristics of different material layers. The multi-layer composite structure achieves the desired wavelength-selective radiation properties while using commercially available materials and fabrication techniques, balancing manufacturing precision with performance.
4Productivity
If environmental convection is optimized to enhance power generation, then the thermoelectric figure of merit improves, but the system becomes more sensitive to environmental conditions
Solution Approach 1:
The patent applies segmentation by separating the heat transfer pathways into distinct convection and radiation zones. The system design isolates the TEG from direct environmental convection effects while maintaining optimal thermal coupling with the radiative cooler. This segmentation allows the system to benefit from enhanced convective cooling at the radiator surface without transmitting all environmental variability to the TEG, thereby improving the thermoelectric figure of merit while mitigating environmental sensitivity through architectural decoupling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves high power density levels exceeding 1.5 W/m2 by optimizing radiative coolers and convection, enabling efficient nighttime power generation suitable for off-grid applications.
Implementation Method 1
electrical power is generated or harvested such as via radiative cooling
Implementation Method 2
spectro-angular selective emitter (characterized by its ability to control or limit the ability to absorb heat power at frequencies and/or angles where emission of the atmosphere is dominant)
Implementation Method 3
Power may be generated via the TEG based on energy directed from the spectro-angular selective emitter
Implementation Method 4
comprehensive optimization/improvement of radiative coolers, environmental convection, and thermoelectric figure of merit
Data Source
AI summary
In certain examples, methods, apparatuses and semiconductor-related structures are directed to nighttime-like electrical power generation by use of a spectro-angular selective emitter as an optimal radiative cooler and a thermoelectric power generator (TEG) having a hot side and a cold side. The cold side may be coupled to the spectro-angular selective emitter which is directed to or facing an atmosphere characterized by an absence of solar light. Power may be generated via the TEG based on energy directed from the spectro-angular selective emitter and by controlling or limiting ability of the spectro-angular selective emitter to absorb heat power at frequencies and/or angles where emission of the atmosphere is dominant.